1.3 Photons Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

What do all electromagnetic waves do in a vacuum?

A

» Travel at the speed of light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the speed of light?

A

» 3.00 x 10^8 ms^-1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the formula for the wavelength of an electromagnetic wave?

A

» Wavelength = speed of light/frequency

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the main parts of the electromagnetic spectrum?

A

» Radio waves => 0.1m

»  Microwaves 0.1m to 1mm

» Infrared 1mm to 700nm

» Visible 700nm to 400nm

» Ultraviolet 400nm to 1nm

» X-rays 10nm to 0.001nm

» Gamma rays < 1nm
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is an electromagnetic wave?

A

» Consists of an electric wave and a magnetic wave which travel together and vibrate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the 3 features of an electromagnetic wave?

A

» At right angles to each other

» In phase with each other

» When 2 waves reach a peak together so they are in step - phase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

When are electromagnetic waves emitted?

A

» A fast-moving electron is stopped or slows downs or changes direction

» An electron in a shell of an atom moves to a different shell or lower energy level

» Electromagnetic waves are emitted as short burst of waves, each burst leaving the source in a different direction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is a photon?

A

» Each burst is a packet of electromagnetic waves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the photoelectric effect?

A

» This is the emission of electrons from a metal surface when light is directed at the surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the photon energy equal to?

A

» E = hf

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is h?

A

» Referred to Planck constant
» Value of 6.63 x 10^-34

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What did Einstein assume?

A

» That the energy of a photon depends on its frequency in accordance with the equation E= hf

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What does a laser beam consist of ?

A

» A laser beam consists of photons of the same frequency

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What does the power of a laser depend on?

A

» The energy per second transferred by the photon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the equation of the power of a laser beam?

A

» Power of the beam = nhf

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

» What is n in the power of the beam equation?

A

» Where n is the number of photons in the beam passing a fixed point each second

» This is because each photo has energy hf. Therefore, if n photons pass a fixed point each second the energy per second is nhf